PRODUCTION OF CHITINASE FROM BIOCONTROL AGENTS: Trichoderma spp.

Document Type : Original Article

Author

Microbial Chemistry Dept., National Research Centre Dokki, Cairo, Egypt

Abstract

Trichoderma spp. play an important role in the destruction of plant pathogenic
fungi, and were found to produce chitinase, which hydrolyzes chitin, a major
component of many pathogenic fungi cell walls. Out of four Trichoderma isolates,
Trichoderma harzianum T3 and T4 strains showed high chitinolytic activity on chitin -
basel agar medium. Factors involved the production of chitinase were investigated.
Maximum enzyme levels of ( 10 t015.9 U I ml) were achieved after six days
incubation at 28°C and initial pH of medium 6.5 The enzyme was produced only in the
presence of colloidal chitin at a concentration of 1 % (w/v) , as a sole carbon source,
suggesting the inducible nature of the enzyme. Trichoderma harzianum T 4 was found
to be very efficient to lyse mycelia of Microphomina phaseolina, Rhizoctonia solani
and Sclerotium rolfsii. Partial purification of chitinase from Trichoderma harzianum T4
was achieved by (NH4)2 S04 precipitation followed by gel filtration using Sephadex G
- 200. The partially purified enzyme was found to be highly active at pH 6.5 and 50°C,
and thermostable at 50°C for 60 min. Mn2+ , Ca2+ and Fe2+ activated the enzyme,
whereas C02+ , Cu2+ , Zn2+ and Hg2+ had different inhibitory effects.

Keywords